Quality-evaluated vitreous silica crucible

ABSTRACT

A quality-evaluated vitreous silica crucible for pulling silicon single crystal is provided, wherein an inner surface of the vitreous silica crucible has regions where surface defects including brown rings are to be generated when pulling silicon single crystal. The regions are distinguished using an infrared absorption spectrum or a Raman shift of the regions, wherein a position of each region and/or a density of the regions are/is specified.

TECHNICAL FIELD

The present invention relates to an inspection method of a vitreoussilica crucible, for predicting a surface defect region of the vitreoussilica crucible and determining a quality of the vitreous silicacrucible.

BACKGROUND ART

In manufacture of a silicon single crystal, the Czochralski method (theCZ method) using a vitreous silica crucible has been employed. In thismethod, on a silicon melt surface at a high temperature of 1420° C.which is the melting point of silicon, a seed crystal is contacted tothe melt surface while rotating in a horizontal direction, then pulledup gradually to manufacture a single crystal; and a vitreous silicacrucible of high-purity is used in order to store the silicon melt.

In recent years, a diameter of the silicon single crystal has beenincreased owing to a demand for an efficiency of a semiconductor deviceprocess. As a result, a diameter of the vitreous silica crucible hasalso been increased. The size of the vitreous silica crucible is such as28 inches (about 71 cm), 32 inches (about 81 cm), 36 inches (about 91cm), and 40 inches (about 101 cm) in diameter. A crucible with adiameter of 101 cm is a huge crucible having a weight of about 120 kg,and the mass of silicon melt contained therein is 900 kg or more. Thatis, during the pulling of silicon single crystal, 900 kg or more siliconmelt of about 1500 degrees C. is contained in the crucible. As a result,a distance from an external carbon heater to the center of the siliconsingle crystal, and an amount of melted polysilicon are increased, whichcauses the temperature in the vitreous silica crucible to become higher.Moreover, the pulling time may be prolonged, and a pulling may last 2weeks or more. In order to maintain the solid-liquid interface of thesilicon melt central part which is contacted with the single crystalnear the silicon melting point of 1420 degrees C., the temperature ofthe vitreous silica crucible is as high as 1450-1600 degrees C. Duringmaybe more than 2 weeks of pulling of silicon single crystal, thedeformation amount for sidewall lowering of rim portion of the vitreoussilica crucible may be 5 cm or more.

Brown cristobalite is generated on the inner surface of the vitreoussilica crucible when contacting with the silicon melt at hightemperature for a long time. As the pulling of a silicon single crystalis proceeded, cristobalite grows in horizontal direction and verticaldirection with respect to the inner surface of the vitreous silicacrucible to form a ring-shaped spot (brown ring). The formed brown ringis likely to be peeled off. The peeled-off brown ring is conveyed intothe silicon single crystal when falling/mixing in the silicon melt. As aresult, the pulled-up silicon ingot is polycrystallized, and the singlecrystallization yield is reduced.

Bubbles contained in the inner surface of the vitreous silica crucibleare also a main cause of decrease in single crystallization yield. Aserosion of the inner surface of the vitreous silica crucible isproceeded, the bubbles in the inner surface of the vitreous silicacrucible enters the silicon melt. The single crystallization yield isreduced by the bubbles in the silicon melt being contained in thesilicon ingot. In addition, under high temperature condition for a longtime, bubbles contained in the inner surface of the vitreous silicacrucible expand significantly. The expanded bubbles cause a deformationof the vitreous silica crucible and an ununiform inner surface. As aresult, a melt surface vibration occurs in the silicon melt, and thesingle crystallization yield is reduced.

In order to solve such a problem, for example, Patent Document 1proposed a method for pulling of silicon single crystal stably bylimiting the number of brown rings in a predetermined position within acertain range (Japanese Patent Application Laid-Open No. 2005-320241).In addition, Patent Document 2 discloses that an amorphous componentratio of the vitreous silica crucible is identified by using laser Raman(Japanese Patent Application Laid-Open No. 2004-492210).

PRIOR ART DOCUMENTS Patent Documents

Patent Documents 1: Japanese Patent Application Laid-Open No.2005-320241

Patent Documents 2: Japanese Patent Application Laid-Open No.2004-492210

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, in Patent Document 1, there still has problems such as it isdifficult to limit the number of brown rings within certain range.

Moreover, in the method described in Patent Document 2, since theconditions for generating the surface defect regions of the brown ringsor the like, are not disclosed until now, it is difficult to figure outin advance the crucible which is likely to generate surface defectregions before shipment.

In addition, the surface defect regions such as the brown rings mayoccur in the crucible inner surface during the pulling of silicon singlecrystal, but the ease of occurrence of surface defect regions differsfor each crucible. That is, even the pulling of silicon single crystalis performed under a substantially same condition; the number ofoccurrence of surface defect regions is different for each crucible.

Accordingly, in consideration of such a situation, an object of thepresent invention is to provide an inspection method of vitreous silicacrucible, for predicting the surface defect region of the vitreoussilica crucible and determining the quality of the vitreous silicacrucible.

Means for Solving the Problems

In order to solve at least one of the above-mentioned problems, thepresent inventors have made extensive research, and found out that byanalyzing in detail a relationship between the infrared absorptionspectrum and Raman shift, the generation of surface defect region of thevitreous silica crucible can be predicted. That is, the presentinvention is an inspection method of vitreous silica crucible,characterized by including: a measurement step of measuring an infraredabsorption spectrum or a Raman shift of a measurement point on an innersurface of the vitreous silica crucible; a determining step ofpredicting whether a surface defect region is generated or not in themeasurement point based on the obtained spectrum to determine thequality of the vitreous silica crucible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a scanning state by a probe 10 on aninner surface 11 of a vitreous silica crucible made of a syntheticsilica powder as raw material.

FIG. 2 is a cross section schematic view illustrating a scanningdirection of the probe 10 in the crucible.

FIG. 3 is a reference infrared spectrum.

FIG. 4 is an infrared spectrum of a vitreous silica.

FIG. 5 is an infrared spectrum predicting a generation of surface defectregion in the vitreous silica crucible before use.

FIG. 6 is an infrared spectrum of the vitreous silica crucible foundsurface defect region after use.

FIG. 7 is a reference Raman shift.

FIG. 8 is a Raman shift of a vitreous silica.

FIG. 9 is a Raman shift predicting a generation of surface defect regionin the vitreous silica crucible before use.

FIG. 10 is a Raman shift of the vitreous silica crucible found surfacedefect region after use.

DESCRIPTION OF THE EMBODIMENTS

According to one aspect of the present invention, there is provided aninspection method, including: a measurement step of measuring aninfrared absorption spectrum or a Raman shift of a measurement point onan inner surface of the vitreous silica crucible; a determining step ofpredicting whether a surface defect region is generated or not in themeasurement point based on the obtained spectrum to determine thequality of the vitreous silica crucible. Hereinafter, the presentinvention will be explained in details.

[Vitreous Silica Crucible]

In the present invention, an inspection object of silica crucible, forexample, as shown in the cross section view of FIG. 2, includes asubstantially cylindrical straight body portion 15 having an opening ontop end and extending in a vertical direction, a curved bottom portion16, and a corner portion 17 connecting the straight body portion 15 withthe bottom portion 16 and having a curvature larger than that of thebottom portion 16.

The vitreous silica crucible is preferred to include a transparent layer20 on the inside and a bubble layer 14 on the outside thereof. Thetransparent layer 20 is a layer formed on the inside of the vitreoussilica crucible, and is substantially bubble-free. The “substantiallybubble-free” means a bubble content rate and bubble diameter at such adegree that a single crystallization yield does not decrease due to thebubbles. Here, the bubble content rate means the volume of the bubblesoccupying in unit volume of the crucible. An image of the crucible innersurface is taken by use of an optical camera, and the crucible innersurface is divided based on a constant volume as a reference volume W1.A volume W2 occupied by bubbles is determined for the reference volumeW1, and calculated by P (%)=(W2/W1)*100. The bubble layer 14, forexample, has a content rate of bubbles contained therein of 0.2% or moreand 1% or less, and the average diameter of the bubbles is 20 μm or moreand 200 μm or less.

The vitreous silica crucible, for example, is manufactured as follows.The silica powder used for manufacturing a vitreous silica crucibleincludes crystallized natural silica powder and amorphous syntheticsilica powder manufactured by chemical synthesis. The natural silicapowder is silica powder manufactured by pulverizing natural mineralmainly composed of a-quartz. The synthetic silica powder can bemanufactured by means of chemical synthesis such as gas phase oxidationof silicon tetrachloride (SiCl₄) (dry synthesis method), or hydrolysisof silicon alkoxide (Si(OR₄)) (sol-gel method).

First, a natural silica powder is applied to a mold used for vitreoussilica crucible. Next, the vitreous silica crucible composed of an innerface layer (synthetic layer) vitrified from the synthetic silica powderand an outer face layer (natural layer) vitrified from the naturalsilica powder, is manufactured by supplying a synthetic silica powder onthe natural silica powder, and melting the silica powder by Joule heatof arc discharge followed by cooling. In the initial stage of an arcmelting step, bubbles are removed by subjecting the silica powder layerto a strong depressurization, thus a transparent vitreous silica layer(transparent layer) is formed, and subsequently, a vitreous silica layer(bubble layer) containing bubbles remained by weakening thedepressurization is formed. Here, the inner face layer formed from thesynthetic silica powder is not necessarily the same with the transparentlayer. Moreover, the outer face layer formed from the natural silicapowder is not necessarily the same with the bubble layer.

The melting of the silica powder is preferably performed so that themaximum temperature of the inner surface of the rotating mold is up to2000-2600 degrees C. When the maximum temperature is lower than 2000degrees C., the gas remained as bubbles during the manufacture of thevitreous silica or in the vitreous silica cannot be removed completely,and the crucible expands remarkably during the pulling of silicon singlecrystal. In addition, when the maximum temperature is higher than 2600degrees C., the viscosity of the vitreous silica is reduced and theshape collapse may occur.

The arc melting is performed, for example, by arc discharge of alternatecurrent three-phase (R phase, S phase, T phase). Therefore, in the caseof alternate current three-phase, three carbon electrodes are used togenerate arc discharge, thereby the silica powder layer is melted. Thearc melting starts the arc discharge at the position where the tip ofthe carbon electrode is positioned higher than the opening portion ofthe mold. Thus, the silica powder layer near the opening portion of themold is melt preferentially. Thereafter, the carbon electrode is loweredto melt the silica powder layer of the straight body portion, the cornerportion and the bottom portion.

[Measurement Step]

In the present invention, an infrared absorption spectrum or a Ramanshift of any measurement point on the inner surface of the vitreoussilica crucible is measured. In order to enhance the accuracy of thequality determination of the vitreous silica crucible, it is preferredto have a plurality of measurement points. By measuring a plurality ofpositions, the number of generation of surface defect regions can bepredicted in advance.

The infrared absorption spectrum can be measured using a Fouriertransform infrared spectrophotometer (FT-IR). By irradiating infraredray on the inner surface of the vitreous silica crucible, it is possibleto investigate a change (molecular vibration) of the relative positionbetween Si—O.

Specifically, for example, the infrared absorption spectrum can bemeasured as follows. The infrared absorption spectrum of the innersurface 11 of the vitreous silica crucible made of synthetic silicapowder as raw material can be measured by using a probe 10 as shown inFIG. 1, which has a light source for irradiating the infrared ray and alight-receiving apparatus for receiving the reflected wave from themeasurement object. The probe 10 can measure the infrared absorptionspectrum of the inner surface 11 in a non-contact manner. As themeasurement method, by providing the probe 10 to the inner surface 11 ofthe crucible 12 in a non-contact manner, and scanning toward thescanning direction 13, the infrared absorption spectrum can be measured.As other scanning mode, for example, a sample scanning mode and a lightsource scanning mode are exemplified. The sample scanning mode is a modeof driving a stage carrying the sample in XY direction to obtain aninfrared absorption spectrum. The light source scanning mode is a modeof applying the light source in XY direction and moving thelight-receiving apparatus matchingly to scan on the sampletwo-dimensionally. Any scanning mode may be employed.

The scanning direction, as shown in FIG. 2, may be a vertical direction18 or horizontal direction 19 of the straight body portion 15. Thescanning is not necessary to be performed on the entire crucible innersurface, and it is also possible to scan only a part of the innersurface 11 of the crucible. For example, it is possible to focus onscanning a position filled with polysilicon melt.

The probe 10 may be for example attached to a robot arm in order toavoid contacting with the inner surface 11. The robot arm may be placedon a rotating table having a rotary encoder which can detect therotation angle. Thus, three-dimensional coordinate can be calculatedeasily. At this time, in order to avoid the contact between the probe 10and the inner surface 11 and keep a constant spacing between the probe10 and the inner surface 11, the robot arm may have a distancemeasurement unit. The distance measurement unit is preferred to have asemiconductor laser capable of measuring the distance to the innersurface of the vitreous silica crucible. The wavelength of the laserlight is not especially limited, and a wavelength of 600-700 nm ispreferable. Moreover, it is possible that, before the measurement ofinfrared absorption spectrum, the three-dimensional shape of thevitreous silica crucible is measured, and the robot arm is moved base onthe measured three-dimensional shape to avoid the contact or to maintainthe spacing between the probe 10 and the inner surface 11. Themeasurement spacing of the infrared absorption spectrum is, for example,1-5 mm.

The Raman shift can be measured by Raman spectroscopy. In the Ramanspectroscopy, light, such as a laser and the like, is irradiated to asample to measure a scattered light caused by a movement of moleculeshaving polarizability. In the vitreous silica, a peak related to adistortion structure due to the Si—O—Si bond angle, is detected.

The Raman shift can be measured by using the probe 10 or robot arm, asthe measurement of the infrared absorption spectrum. The condition ofthe Raman measurement can be, for example, laser wavelength: 785 nm (100mW), exposure time: 10 seconds, number of times of integration: 1 time.In the case of measuring the FT-IR measurement and the Ramanmeasurement, either one can be measured previously, or both can bemeasured simultaneously.

[Determining Step]

In the determining step performed in the present invention, whether asurface defect region is generated in a measurement point or not, ispredicted on the basis of the obtained spectrum. The “surface defectregion” refers to an abnormal part or region generated in the vitreoussilica crucible, which affects the yield of silicon single crystal. Forexample, it is a brown ring or bubble, or the like. Whether a surfacedefect region occurs or not, can be detected based on a spectrum peak.As the spectrum peak, for example, it may be all of or a part of theobtained spectrum peaks. In addition, it may be a characteristic peakwithin certain wavenumber range, and in this case, whether a surfacedefect region is generated or not can be predicted by only certainwavenumber range (band) of interest.

Specifically, for example, a generation of surface defect region can bepredicted on the basis of following three methods and a combinationthereof.

(1) Prediction Based on an Infrared Absorption Spectrum of CertainWavenumber

The analysis result by the present inventors is to find that, thepresence of peaks between wavenumber 1080-1100 cm⁻¹ and/or peaks betweenwavenumber 1150-1250 cm⁻¹, is the characteristic range of the generationof surface defect region. Therefore, it is possible to predict whether asurface defect region is generated or not by the presence of peaks inthese ranges. Specifically, when there is a peak or there is no peakbetween wavenumber 1080-1100 cm⁻¹, it is possible to predict ageneration of surface defect region. Also, when there is a peak betweenwavenumber 1150-1250 cm⁻¹, it is possible to predict a generation ofsurface defect region. In the case of determining quantitatively, it isalso possible to carry out a determination by setting a threshold.

(2) Prediction Based on a Raman Spectrum of Certain Wavenumber

The analysis result by the present inventors is to find that, thepresence of peaks between Raman shifts from 500 to 550 cm⁻¹, is thecharacteristic range of the generation of abnormal site. Therefore, itis possible to predict whether a surface defect region is generated ornot by the presence of peaks in these ranges. In the case of determiningquantitatively, it is also possible to carry out a determination bysetting a threshold. Specifically, when a peak is present, it ispossible to predict a generation of surface defect region.

(3) Prediction by a Comparison with Reference Spectrum

Whether a surface defect region is generated in a measurement point ornot, is predicted by comparing the obtained spectrum with a referencespectrum prepared in advance. Here, the “reference spectrum prepared inadvance” refers to, for example, a spectrum in the case of that in ameasurement point of a vitreous silica crucible before pulling ofsilicon single crystal, a surface defect region is generated in themeasurement point after the pulling of silicon single crystal. When thesurface defect region is a brown ring, not only the region of the brownring, but the center and a region near the center thereof are alsoincluded. The comparison using the reference spectrum prepared inadvance may be compared immediately after measuring the spectrum ofinner surface 11, or may be compared after measuring a plurality ofmeasurement points. As a result of the comparison, the two spectra aredetermined to be equal or not, and in the case of unequal, a generationof surface defect region can be predicted. In the case of determiningquantitatively, it is also possible to carry out a determination bysetting a threshold. The comparison with the reference spectrum mayutilize the predictions based on the (1) and (2) and compare onlycertain wavenumber range, to predict the generation of surface defectregion.

By using previously accumulated data (the reference spectrum) undercertain conditions, it is possible to carry out a comparison with higheraccuracy in the practice under the same conditions. In addition, it isalso possible to create a reference spectrum with high accuracy byfeeding back the data.

From the prediction obtained as above, the quality of vitreous silicacrucible is evaluated. For the evaluation of quality, for example, inthe case of one position of measurement point, when a generation ofsurface defect region is predicted, it can be evaluated as a defectiveproduct. In the case of a plurality of measurement points, when ageneration of a predetermined number of surface defect regions ispredicted, it can be evaluated as a defective product.

In addition, in the case of a plurality of measurement points, thequality of the vitreous silica crucible can be determined based on apredicted generation number of the surface defect regions per unit areaof inner surface of the vitreous silica crucible. The predictedgeneration number of the surface defect regions per unit area may be anaverage value. Further, it is possible to calculate the predictedgeneration number of the surface defect regions per unit area of certainportion (for instance, straight body portion, corner portion, and bottomportion) of the vitreous silica crucible, and the case of exceedingcertain value is determined as a defective product. In this way, whethera vitreous silica crucible is defective or not can be easily determinedeven in a short measurement time.

[Method of Manufacturing Silicon Ingot]

A silicon ingot can be manufactured by (1) in a vitreous silica crucible12, melting polysilicon to produce silicon melt, and (2) pulling upwhile rotating a seed crystal with the tip of the silicon seed crystalbeing soaked in the silicon melt. The shape of the silicon singlecrystal was made from: a cylindrical silicon seed crystal from the upperside, following a conical silicon single crystal, a cylindrical siliconsingle crystal having the same diameter as the bottom surface of theupper conical silicon single crystal, and a conical silicon singlecrystal having a vertex orienting downward.

The pulling of silicon ingot is usually performed at about 1450-1500degrees C. After the pulling of silicon single crystal, the innersurface of the crucible is observed to confirm the presence of a brownring. It is also possible to obtain the three-dimensional coordinates ofthe confirmed brown ring, and collate with the data during manufacturingthe vitreous silica crucible 12 to make a data feedback.

EXAMPLES

(Manufacture Example) Manufacture of Vitreous Silica Crucible

A vitreous silica crucible was manufactured on the basis of a rotatingmold method. The mold opening diameter was 32 inch (81.3 cm), theaverage thickness of silica powder layer deposited on the mold innersurface was 15 mm, and the arc discharge was performed with threeelectrodes at 3-phase alternating current. The energization time of thearc melting step was 90 minutes, output was 2500 kVA, and the evacuationof the silica powder layer was started in 10 minutes from the start ofenergization. Three vitreous silica crucibles were manufactured. In themanufactured vitreous silica crucible, polysilicon was added to melt,and a silicon single crystal was pulled up.

(Reference Example 1) FT-IR Measurement and Raman Measurement

After the pulling of silicon single crystal, FT-IR measurement and Ramanmeasurement of the brown ring generated on the inner surface of thecrucible were performed.

FIGS. 3 to 6 are the results of measuring the microscopic infraredreflection spectrum using a microscopic infrared reflection measurementapparatus. The condition was: resolution: 4 cm⁻¹, number of times ofintegration: 64 times (about 30 seconds). FIG. 3 is a referencespectrum, and FIG. 4 is a spectrum of a vitreous silica. FIG. 6 is aspectrum of vitreous silica crucible found of surface defect regionafter use, and FIG. 5 is a spectrum predicting a generation of surfacedefect region in the vitreous silica crucible before use.

As shown in FIG. 6, for the surface defect region, peaks in vicinity ofwavenumber 1210-1230 cm⁻¹ and wavenumber 1090-1094 cm⁻¹ were present. Onthe other hand, in the spectrum of the vitreous silica (not surfacedefect region), peak of the wavenumbers were not seen, and a peak invicinity of wavenumber 1120 cm⁻¹ was present. This peak was not seen inFIG. 6. Therefore, it is understood that the peak between wavenumber1080-1100 cm⁻¹ and peak between wavenumber 1150-1250 cm⁻¹ can be deemedas characteristic peaks, and also can be used as the reference spectrum.

FIGS. 7 to 10 are the results of measuring the Raman shift of thesurface defect region using a dispersive type micro-Raman apparatus. Thecondition was: laser wavelength: 785 nm (100 mW), exposure time: 10seconds, number of times of integration: 1 time. FIG. 7 is a referencespectrum, and FIG. 8 is a spectrum of vitreous silica. FIG. 10 is aspectrum of vitreous silica crucible found of surface defect regionafter use, and FIG. 9 is a spectrum predicting a generation of surfacedefect region in the vitreous silica crucible before use.

As shown in FIG. 9, for the surface defect region, a peak in vicinity ofRaman shift 520-530 cm⁻¹ was present. On the other hand, in the vitreoussilica (not surface defect region), the peak in Raman shift 520-530 cm⁻¹was not present. Therefore, it is understood that the peak between Ramanshifts from 500 to 550 cm⁻¹ can be deemed as characteristic peak, andalso can be used as the reference spectrum.

Examples 1-3

The inner surfaces of three unused vitreous silica crucibles obtained inManufacture Example were subjected to FT-IR measurement and Ramanmeasurement. The three-dimensional shape of the inner face shape of thevitreous silica crucible was obtained, and the measurement on thestraight body portion, the corner portion and the bottom portion of thevitreous silica crucible was carried out. The measurement point wasselected arbitrarily from the region (a region of about 5 cm² square(about 25 cm²) of above-mentioned portions of the vitreous silicacrucible, and 20 points were measured respectively. The measurementrange (spot diameter) of the FT-IR measurement and Raman measurement is20 μm.

With respect to the FT-IR measurement, a spectrum with thecharacteristic peaks present in vicinity of wavenumber 1210-1230 cm⁻¹and wavenumber 1090-1094 cm⁻¹ was observed. The measurement pointobserved of the characteristic peaks was deemed as the measurement pointpredicted of surface defect region generation, and the correspondentcoordinates were stored in a storage device, thus the predictedgeneration index of the surface defect region was calculated. Thegeneration index is a value obtained by dividing the total number ofmeasurement positions by the observed number of the surface defectregions. The results are shown in Table 1.

With respect to the Raman measurement, a spectrum with thecharacteristic peak present in vicinity of Raman shift 520-530 cm⁻¹ wasobserved. The measurement point observed of the characteristic peaks wasdeemed as the measurement point predicted of surface defect regiongeneration, and the correspondent coordinates were stored in a storagedevice, thus the predicted generation index of the surface defect regionwas calculated. The generation index is a value obtained by dividing thetotal number of measurement positions by the observed number of thesurface defect regions. The results are shown in Table 1.

TABLE 1 crucible 1 crucible 2 straight straight body corner bottom bodycorner bottom portion portion portion portion portion portion IR RamanIR Raman IR Raman IR Raman IR Raman IR Raman Predicted 0.10 0.15 0.150.15 0.10 0.20 0.05 0.05 0.05 0.10 0.10 0.15 generation index crucible 3straight body corner bottom portion portion portion IR Raman IR Raman IRRaman Predicted 0.10 0.15 0.10 0.10 0.05 0.10 generation index

After the FT-IR measurement and Raman measurement, a pulling of siliconsingle crystal using the measured vitreous silica crucible was carriedout. On the basis of the coordinates corresponding to the characteristicpeaks of the FT-IR measurement and Raman measurement before the pullingof single crystal, the inner surface of the vitreous silica crucibleafter the pulling of single crystal was confirmed. As a result, in thecoordinates in which the characteristic peaks were present, surfacedefect regions on the inner surface of the vitreous silica crucibleafter the pulling of single crystal were observed. Table 2 is a list ofthe generation number of surface defect regions per about 25 cm² of themeasurement region.

TABLE 2 Crucible 1 Crucible 2 Crucible 3 straight straight straight bodycorner bottom body corner bottom body corner bottom portion portionportion portion portion portion portion portion portion generation 25 2333 10 9 20 22 15 18 number

From the above results, it is understood that, in the case of FT-IRmeasurement, the peak in vicinity of wavenumber 1210-1230 cm⁻¹ and/orpeak in vicinity of wavenumber 1090-1094 cm⁻¹ can be used as adetermination criterion to determine whether a crucible is likely togenerate a surface defect region or not. In the case of Ramanmeasurement, the peak of Raman shift 520-530 cm⁻¹ can be used as adetermination criterion to determine whether a crucible is likely togenerate a surface defect region or not. Further, by combining thecriterion of FT-IR measurement and the Raman measurement, it is possibleto inspect the generation site of the surface defect region moreprecisely.

According to the inspection method of the present invention, it ispossible to specify the generation position of the surface defect regionbefore the pulling of silicon single crystal. Therefore, the generationratio or density of the surface defect regions can be predicted inadvance, and the quality inspection of the surface defect region for thevitreous silica crucible before shipment can be performed, which was notpossible so far. Further, the quality inspection of a vitreous silicacrucible required certain density of surface defect regions, can beperformed.

This application is a continuation of U.S. patent application Ser. No.15/377,963, filed Dec. 13, 2016 which is a continuation of U.S. patentapplication Ser. No. 14/901,030, filed Dec. 27, 2015, now U.S. Pat. No.9,557,276, which is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application PCT/JP2013/067946, filed Jun. 30, 2013, eachdisclosure of which is herein incorporated by reference in its entirety.The International Application was published under PCT Article 21(2) in alanguage other than English. The applicant(s) herein explicitlyrescind(s) and retract(s) any prior disclaimers or disavowals made inany parent, child or related prosecution history with regard to anysubject matter supported by the present application.

What is claimed is:
 1. A quality-evaluated vitreous silica crucible forpulling silicon single crystal, wherein an inner surface of the vitreoussilica crucible has regions where surface defects including brown ringsare to be generated when pulling silicon single crystal, said regionsbeing distinguished using an infrared absorption spectrum or a Ramanshift of the regions, wherein a position of each region and/or a densityof the regions are/is specified.
 2. The quality-evaluated vitreoussilica crucible according to claim 1, wherein the position of eachregion corresponds to a position having a peak in the infraredabsorption spectrum corresponding to wavenumber 1080-1100 cm⁻¹ and/orwavenumber 1150-1250 cm⁻¹.
 3. The quality-evaluated vitreous silicacrucible according to claim 1, wherein the position of each regioncorresponds to a position having a peak in the Raman shift correspondingto Raman shift 500-550 cm⁻¹.
 4. The quality-evaluated vitreous silicacrucible according to claim 1, which has a substantially cylindricalstraight body portion having an opening on a top end and extending in avertical direction, a curved bottom portion, and a corner portionconnecting the straight body portion with the bottom portion and havinga curvature larger than that of the bottom portion, wherein the densityof the regions is specified in each of the body portion, the curvedbottom portion, and the corner portion.